Catalysts and reactors including catalysts can be used for a variety of purposes. For example, catalysts can be used to lower a temperature required for a reaction to take place, to increase a reaction rate at a temperature, and/or to drive particular reactions relative to other reactions that might otherwise be favored in the absence of a catalyst.
Catalysts are often employed in gas-to-liquid (GTL) and coal-to-liquid (CTL) reactions to form liquid hydrocarbons from natural gas (GTL) or coal (CTL). In these cases, a carbon source, such as natural gas or coal is exposed to an oxidation or gasification process to produce synthesis gas (syngas), including hydrogen and carbon monoxide. Fischer Tropsch reactions (collectively called Fischer Tropsch process), using a suitable catalyst, can convert the hydrogen and carbon monoxide to products, such as synthetic oils and fuels. The products formed using a Fischer Tropsch process may be desirable because the products can have a relatively high energy density, may be relatively pure, and can be easily transported.
Liquid fuels can be produced from a Fischer Tropsch process on catalytic surfaces at pressures around 2-4 MPa and moderate temperature of about 200° C.-240° C. Primary reaction products are typically straight chain paraffin's and tight control of reactor conditions can increase this product fraction and improve reactor productivity. However, a Fischer Tropsch process is highly exothermic with a heat of reaction of about −157 kJ/mol and up to −247 kJ/mol for CH4 production, making temperature control difficult in most conventional reactors. Thermal gradients provide additional control difficulties. As reactor temperatures increase for a Fischer Tropsch process, selectivity favors formation of CH4, which, in turn, causes more heat to be released and may result in thermal instabilities and a “runaway” reaction. The Fischer Tropsch process research community has worked to understand and improve Fischer Tropsch process catalyst activity and selectivity. However, at an industrial scale, temperature control is a primary concern. In the last ten years, new microstructured reactors and monolithic structures have been proposed for application in a Fischer Tropsch process and have shown promise in addressing this major challenge. But in practice, such complex designs have been impractical for industrial scale [1-3]. Accordingly, improved catalysts, catalyst structures, and reactors, which may be used for a Fischer Tropsch process or other applications, and methods of forming the catalysts, catalyst structures, and reactors, are desired.